Since we use Gitlab for private repositories and Github for public ones, the main irritation I find is that even those two aren't completely compatible. From a

Since we use Gitlab for private repositories and Github for public ones, the main irritation I find is that even those two aren't completely compatible. From a standards perspective, the "official" seems to be supported everywhere but when you start adding in "extensions/variants" all bets are off. You might be able to write most blog posts with the official version but I like TODO lists, tables, etc (without resorting to inline HTML).